chore: add Cloud SQL samples env vars as secrets

[jackwotherspoon]

Add a new secret to store Cloud SQL samples secrets. This secret will be setup as part of the build setup script.

The secret manager secrets live in a project owned by @GoogleCloudPlatform/cloud-sql-connectors who maintain the /cloud-sql samples.

Fixes #12987

[ghost]

Hi team,

I'm currently reviewing this pull request and will provide my feedback shortly. In the meantime, here's a summary for you and other reviewers to quickly get up to speed:

This pull request, authored by jackwotherspoon, aims to add Cloud SQL samples environment variables as secrets. The primary goal is to improve security by storing sensitive information in a more secure manner.

Here's a breakdown of the changes:

• Added a new secret: A new secret, python-docs-samples-cloud-sql-secrets, is added to store Cloud SQL samples secrets. This secret is managed by the @GoogleCloudPlatform/cloud-sql-connectors team.
• Modified run_tests.sh: The run_tests.sh script (.kokoro/tests/run_tests.sh) is updated to source the new Cloud SQL secrets file (testing/cloudsql-samples-secrets.sh). Specifically, lines 111, 116, and 122 were modified to include the new secret file. Lines 214 and 215 were also updated to remove the new secret file after testing.
• Modified decrypt-secrets.sh: The decrypt-secrets.sh script (in scripts/) is updated to retrieve and store the new Cloud SQL secret. Lines 46-52 were added to accomplish this.

This addresses issue #12987.

---

And now, a little haiku to lighten the mood:

Secrets safe and sound,
Code runs smoothly, free from fear,
Review now complete.

Thanks,
Gemini

[ghost]

This pull request introduces a new secret to store Cloud SQL samples secrets, which is a positive change for security. The implementation is straightforward and addresses the issue of managing sensitive information effectively. The commit message clearly explains the purpose and context of the changes, and the link to the related issue provides additional context.

[davidcavazos]

Failing tests seem unrelated

[davidcavazos]

The tests that depend on these new secrets seem to be passing, other failing tests are most likely flaky or currently broken. I think this should be safe to merge.

cloud-sql/mysql/client-side-encryption................................[ SUCCESS]
cloud-sql/mysql/sqlalchemy............................................[ SUCCESS]
cloud-sql/postgres/client-side-encryption.............................[ SUCCESS]
cloud-sql/postgres/sqlalchemy.........................................[ SUCCESS]
cloud-sql/sql-server/client-side-encryption...........................[ SUCCESS]
cloud-sql/sql-server/sqlalchemy.......................................[ SUCCESS]

[davidcavazos]

Failing tests are unrelated. SQL tests are passing which means this change is not breaking anything new.